Construction of protein expression plasmids containing the entire envelope gene sequence of the human T-cell leukemia virus type-I (HTLV-I) provirus, as well as DNA fragments representing subregions of this gene, has been accomplished. These plasmids were put into the bacterial expression vector, pJL6, or its derivatives, pJLA16 and pCJX. Work pertaining to the construction of hybrid plasmids containing DNA sequences coding for the putative polypeptides of the HTLV-I genome has also been initiated. Examination of the c-myc locus of the human lymphoblastoid cell line NC37 has revealed: (1) a rearranged c-myc locus, (2) an overexpression of c-myc mRNA, and (3) that it is tumorigenic in nude mice. A cosmid genomic library of NC37 cell DNA was constructed for the studies relating to the structure and regulation of the human c-myc locus. Efforts to isolate and characterize the "primordial" c-myc oncogene in slime mold, and other prokaryotic species, are continuing. Preliminary characterization of putative clones from an EcoRI library of the slime mold, Dictyostelium discoideum, is under investigation using specific subclones derived from our cloned myc constructs.